Dr. Imre Tamás Horváth won the PhD thesis prize of AFVL

During its General Assembly of 15 September 2016, the AFVL (Association Francophone de Vélocimtérie Laser) has awared the PhD thesis prize of AFVL to Dr. Imre Tamás Horváth. This prize honors outstanding PhD research works on the field of optical technics in fluid mechanics.

His thesis is entitled: "Development and applications of the Light Extinction Spectroscopy technique for characterizing small particles" and was defended at the Université Libre de Bruxelles in October 2015.

The purpose of his thesis is to develop and apply an experimental technique for measuring the size of nanoparticles and nanodroplets in a flow environment. The developed non-intrusive, optical method is called Light Extinction Spectroscopy (LES) and it allows to determine the size of particles from measuring their light transmission spectrum on the Ultraviolet-Near-Infrared range. The most crucial part of the development work is to obtain a reliable data processing method, which is based on the regularized solution of an ill-conditioned inverse problem. The developed method is first tested using synthetic data, which allows to determine the measurement range and also the measurement errors caused by various sources. This is followed by performing laboratory experiments for validating the LES technique. Validation measurements using calibrated particles and a reference instrument shows that sizing errors are in the order of 5-10%. Afterwards, the technique is applied for characterizing the Brownian coagulation process of nanodroplets, where the growth rate of droplets is successfully measured and is found to agree with theoretical expectations. Next, the LES technique is applied to coagulating solid particles, where the growth rate of these complex non-spherical objects is retrieved. Finally, a particle monolayer is deposited on an air-water interface and it is shown that the LES technique can retrieve the particle-water contact angle, which allows the characterization of nanoparticle wettability and the study of the related interesting physical phenomena.